The exhaust port on the bottom of the valve is what lets air out of the piping after the brake application is released. If air is there when it shouldn't be, it could be because the foot pedal isn't letting off all the way, but it's probably coming from the R-8 relay valve at the rear of the bus. The upper section of the E valve is the primary section and works the rear brakes by sending air through a small line to the R-8 valve. If you disconnect and cap off the small line at the R-8 end, the exhausting air may stop - if so that tells you it's the rear brakes. The relay valve gets it's main air supply from the primary service tank to feed the rear brake cannisters, but it's remote-controlled by the treadle valve through the small relay line. Air could be feeding back from the relay valve, is what I am thinking.

Just noodling the issue, I'm not that familiar with dual brake systems.

Friday we replaced the treadle valve under the driver seat, then we found feedback through the push/pull valve while in park. We replaced the push/pull valve without success. Now we spent all day Saturday removing the inverter valve in the back. With stuck bolts and broken lines it took most of the day. We cleaned the inverter valve and hope to re-install that today with hopes that the problem is fixed.

If anyone has ideas I'm all ears....very frustrating day yesterday. Not knowing if we're even doing the right thing.

Dave

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1989 MCI-102 A3DD 6V92 Turbo, AlisonTons of stuff to learn!Started in Cheboygan, Michigan (near the Mackinaw Bridge). Now home is anywhere we parkhttp://dave-amy.com/

Friday we replaced the treadle valve under the driver seat, then we found feedback through the push/pull valve while in park. We replaced the push/pull valve without success. Now we spent all day Saturday removing the inverter valve in the back. With stuck bolts and broken lines it took most of the day. We cleaned the inverter valve and hope to re-install that today with hopes that the problem is fixed.

If anyone has ideas I'm all ears....very frustrating day yesterday. Not knowing if we're even doing the right thing. Dave

OK, I wouldn't know a DD3 if you hit me over the head with one, but if you've got feedback through the push/pull parking/emergency valve, that would make me look more and more a leakage between "service" and parking chambers on one or more wheel cylinders. Did you get a GOOD clamp off of air through the braided brake hoses running to each of the chambers when you did the test that Clifford described above?

You did not pinch off the air supply to the park brake at the rear brakes!! That is the first thing to do. A bad diaphragm on one/both will allow air to escape through the R-8. Got mine from Luke, while in there one of the big ones was chafing so changed it. 717-582-78three 3